It's new, came with Chronicles vol 1. Therefore I don't see it as canon because it does not have a well established lore like the four big baddies we have left (Sargeras, Zul, Azshara and N'zoth)
I'm disappointed that they took WoW in this direction just for the sake of creating more expansions. True artists would've ended it after Sargeras, but they're a company in the end, so they're doing it for the money.
I think it would've been way better had they ended it at Sargeras and then given us filler expansions afterwards until their next MMO.
Though it depends on who you ask, I personally think of the void lords as filler content because it was just created to give us more expansions.